17.10 - Changing the Value for Two Response Buffers - Call-Level Interface Version 2

Teradata® Call-Level Interface Version 2 Reference for Workstation-Attached Systems

Product
Call-Level Interface Version 2
Release Number
17.10
Release Date
October 2021
Content Type
Programming Reference
Publication ID
B035-2418-061K
Language
English (United States)
If the value provided is not appropriate for the application, perform the following steps before calling DBCHCL for the Connect, Run Startup, or Initiate Request function:
  1. Change Options to 'Y'.
  2. Set the Two Response Buffers value to the appropriate value:
    • Y, if the response is to be double-buffered.

    • N, if a single buffer is to be used for the response.

Double buffering is useful when large responses are expected from the database and large response buffers are used. Substantial improvements in response time can result by transferring the next buffer-full of response data from the database while the previous buffer-full is being accessed by the application program.

The response buffer or buffers are re-stocked automatically by DBCHCL. The application program may have to wait for data to arrive if the application program is consuming the data faster than the database can re-stock the buffer, but it does not have to arrange for data to arrive.

The connect request’s response is not double-buffered, even if Two Response Buffers is set to Y when DBCHCL is called for the Connect function. However, any other request’s responses on that session are double buffered, unless the setting of Two Response Buffers is changed before the request is submitted.

Although the value of Two Response Buffers is read and stored by the Connect function, it is not used for the connect operation itself.

Two Response buffers are ignored if the fetch request is for LOB or cursor repositioning responses.